Methods for fixing an element on a cylindrical part of a shaft are already known.
In many cases, as described for example in U.S. Pat. No. 4,549,341, an element with an inner passage whose inner diameter is smaller than the outer diameter of the aforesaid part of the shaft is taken.
In order to be able to apply such a type of element over the cylindrical part of the shaft, these known methods make use of the principle that objects expand when being heated and shrink when being cooled.
By heating the element and cooling the aforesaid part of the shaft, the difference between the inner diameter of the element and the outer diameter of the shaft is hereby eliminated, such that the element can be pushed over the cylindrical part of the shaft, after which, as the element is cooled down and the shaft is heated again, a shrink fit can be obtained.
A first disadvantage of these known methods is that they can only be applied with materials having a sufficiently high thermal expansion coefficient.
Another disadvantage of this known method is that the element must be strongly heated to obtain a sufficient expansion, which may cause damage to the element or even to the shaft.
With elements in the shape of permanent magnets, said heating may change the magnetism of the magnets.
Also with elements made of a polymer or plastic, such a heating may be fatal, as a result of which the field of application of this known method is restricted.
Further, heating large elements in a consistent manner, for example metal rings or the like, is very expensive and not simple.
Moreover, there is a danger with said known method in that, when applying the heated element on the shaft, the element will cool down too fast and will get stuck on the shaft before it has been put in the right place, with all the ensuing consequences.
With other known methods for applying an element on a shaft, as known for example from U.S. Pat. No. 5,188,478 and U.S. Pat. No. 6,104,115, the part of the shaft is provided with a conical outer surface on which has been provided an element with a complementary conical passage.
A disadvantage of such conical embodiments is that they are expensive.
Even if the element is made of a fibre-reinforced composite, for example, it will be hard to produce large numbers due to the conical shape of the element.
For, when manufacturing for example a conical composite ring, the inner conicity of the ring will be obtained by winding a strip of composite around a conical mandrel which is restricted to the length of one ring because of the required conicity.
On the contrary, it is easy to cut a cylindrical composite ring from a much longer cylindrical tube, whereby such a cylindrical tube can be obtained by winding a strip of composite around a cylindrical mandrel whose length may be chosen at random.
As a result, it is intrinsically much easier to produce cylindrical rings than conical rings.